I use d3.js exactly as shown here but with different data value.
When the graph is first shown all elements are scattered and for around a second rapidly move towards their position. This looks nice in the sample, but for my data it does not look so nice. Any way to turn it off so that nodes start in their designated place? Any way to customize this entry visualization?
You can loop through the nodes array and set the .x/.y and .px/.py values to an initial position that you want the nodes in, and by doing so will limit the amount they need to move in their initial layout. If you turn off the force-directed algorithm (the tick() function) then you can apply standard .transtion().duration(500).attr("transform", xx) behavior to the nodes and links to make them animate in a manner you prefer before or after running the force-directed algorithm, but make sure you set the .x/.y and .px/.py attributes to their final position, otherwise they will be reset as soon as you .tick()
Related
I'd like to transition between curve types using D3.js.
Take a look at this block. The data stay the same but the curve type changes. I was expecting the paths to maintain their approximate positions on the plane -- the data stay the same, after all -- but they don't. The paths appear to be redrawn, although I don't understand why with basis to linear the paths seem to be redrawn from left to right whilst with linear to basis the paths seem to be redrawn from right to left.
I've read Mike Bostock's post on Path Transitions, but I think this is a slightly different problem. There, the data change but the curve type remains the same. Here, the data stay the same but the curve type changes.
Thanks in advance for any help!
To understand why you have such a strange transition, let's compare the d attribute of the paths using a curveBasis and a curveLinear.
First, a curveBasis:
d="M0,101.2061594964L45.48756294826797,89.52282837400001C90.97512589653594,77.83949725160001,181.95025179307189,54.47283500680002,271.46268884480395,84.08731623460001C360.975125896536,113.70179746240001,449.0248741034641,196.2974221628,538.5373111551961,222.09899531679994C628.0497482069281,247.90056847079998,719.0248741034642,216.90809007840002,764.512437051732,201.4118508822L810,185.915611686"
Now a curveLinear (same data):
d="M0,101.2061594964L272.92537768960784,31.10617276200003L537.0746223103922,278.89304686319997L810,185.915611686"
As you can see, the path is way simpler with curveLinear. So, the strange transition is the expected behaviour.
A possible solution is using a path interpolation, as proposed in this code from Mike Bostock.
Here is your bl.ocks with a path interpolation: http://blockbuilder.org/anonymous/02125b1fb145a979e53f369c4976a772
PS: If you want to avoid that strange transition when you load the page (all paths coming from the top left corner), draw them the first time using a regular attr method.
I made a simple tree structure and displayed it using D3.js. When nodes become too many, it's impossible to see any text.
Fig1 Fig2
I could make an image out of the svg, then render it instead of displaying the tree by d3js and finally using a magnifier to zoom in. I don't know if it can actually work; is there a better and working way to do it?
Well first of all I would recomend placing your lable below the nodes rather than to the right as that will win you some space back but that won't really solve your problem.
I would recomend either making your tree colapse by node
or defining the space between the nodes as a function of how many children there are. For this, you will need to recursively count the children in your tree. You can see how to do that in an answer I gave here
There are likely other solutions but those are the two that jump out at me as the best.
I got a data set that where each sample has a size (0-1000) and a value (grade 1-5). I want to visualise the data with circles of different sizes along a line (domain axis), much like:
http://www.nytimes.com/interactive/2013/05/25/sunday-review/corporate-taxes.html?_r=1&
(note that circles even with the same effective taxrate do not overlap)
Example data:
sample 1: size 300 value 3.2
sample 2: size 45 value 3.8
sample 3: size 4400 value 4.0
sample 5: size 233 value 0.2
sample 6: size 4000 value 4.2
How can the data above be visualised using circles on a line (size decides diameter, value decides approximate position on the line) so that circles do not overlap?
I've been looking at D3's packing layout, but from what I can tell it doesn't support this out of the box. Anyone got any ideas on how to approach this?
Oooh, this one was a puzzle...
If you look at the code for the NYTimes graphic, it uses pre-computed coordinates in the data file, so that's not much use.
However, there's an unused variable declaration at the top of the script that hints that the original version used d3.geom.quadtree to lay out the circles. The quadtree isn't actually a layout method; it is used to create a search tree of adjacent nodes, so that when you need to find a node in a given area you don't have to search through the whole set. Example here.
The quadtree can therefore be used to identify which of your datapoints might be overlapping each other on the x-axis. Then you have to figure out how much you need to offset them in order to avoid that overlap. The variable radii complicate both functions...
I've got a test case implemented here:
http://fiddle.jshell.net/6cW9u/5/
The packing algorithm isn't perfect: I always add new circles to the outside of existing circles, without testing whether they could possibly fit closer in, so sometimes you get significant extra whitespace when it is just the far edges of circles bumping into each other. (Run it a few times to get an idea of the possibilities -- note that I've got x-variables distributed as random normal and r-variables distributed as random uniform.) I also got a stack overflow on the recursive methods during one iteration with N=100 -- the random distribution clearly wasn't distributed well enough for the quadtree optimization.
But it's got the basic functionality. Leave a comment here if you can't follow the logic of my code comments.
--ABR
Update
New fiddle here: http://fiddle.jshell.net/6cW9u/8/
After a lot of re-arranging, I got the packing algorithm to search for gaps between existing bubbles. I've got the sort order switched (so that biggest circles get added first) to show off how little circles can get added in the gaps -- although as I mention in the code comments, this reduces the efficiency of the quadtree search.
Also added various decoration and transition so you can clearly see how the circles are being positioned, and set the r-scale to be square root, so the area (not radius) is proportional to the value in the data (which is more realistic, and what the O.P. asked for).
D3's packing layout is not the answer here. It places circles in a spiral fashion around the existing group. Here's me reverse-engineering the algorithm behind packing layout:
I would suggest a force layout-based approach. That way, you can give your nodes force towards a gravitational center, and then let gravity do its thing.
Force layouts (e.g. Clustered Force Layout I) are usually animations, so you'll want to apply a static force layout.
I've wrapped up this approach in an example block, which looks like this:
The number of nodes in my d3 graph is too large. So I built a zoom mechanism in that graph. Now the problem is, I just cannot display text for each nodes since they will overlap each other. However when I zoom in to the nodes, the space is enough to display texts.
So how do I show texts when the space is enough to show all of them without overlapping?
I have had this same problem in the past. Unfortunately optimal label placement is not an easy problem. To mitigate overlap effects one option is to use a restricted force layout for label placement. You can also try using callouts to allow the labels to move farther away from the nodes.
In the past I have implemented a sort of greedy collision detection based algorithm that goes something like:
sort the labels in decreasing priority
for each label in the list // so most important first
if the label does not overlap any placed labels
place the label and add it to my collision data structure (e.g. quad tree)
else
hide the label
Obviously this will have some non-optimal cases and it can be slow if you have a lot of animations going on. But when you have the option to zoom in to see more label and if your absolute number of labels is not too high then it works quite well. There are also a number of obvious ways to speed it up like restricting testing to only labels within the view (but then you need to update on pan).
You may find some helpful suggestions here including an implementation of collision detection.
I created a network in D3.js that updates links (both remove and add) as you move the slider back and forth.
However the edges overlap the nodes (as in edges are drawn ontop of the nodes...)
I think https://github.com/agfk/knowledge-maps/issues/1 looks at the issue but I'm not quite sure what it means.
I might have something to do with the order that the lines are drawn as opposed to the nodes but I don't know how to fix that. Svgs also don't come with z-indexes so I can manipulate it through css.
Any help would be appreciated! Thanks!
This link discusses how to determine the order in which elements are drawn. In your case, perhaps you want to draw the edges first and then the nodes:
https://groups.google.com/forum/?fromgroups=#!topic/d3-js/JCXKef_GRCQ